Ctenochelidae Manning and Felder, 1991

Poore, Gary C. B., Dworschak, Peter C., Robles, Rafael, Mantelatto, Fernando L. & Felder, Darryl L., 2019, A new classification of Callianassidae and related families (Crustacea: Decapoda: Axiidea) derived from a molecular phylogeny with morphological support, Memoirs of Museum Victoria (Mem. Mus. Vic.) 78, pp. 73-146 : 115-118

Ctenochelidae Manning and Felder, 1991

Figures 16 , 17

Ctenochelinae Manning and Felder, 1991: 784.— Poore, 1994: 103.— Sakai, 1999c: 87.— Sakai, 2005b: 235.

Gourretiinae Sakai, 1999c: 95.— Sakai, 2017a: 1124.

Gourretiidae .— Sakai, 2004: 556.— Sakai, 2005b: 217.— Sakai, 2011: 507–508.— Sakai, 2017a: 1124–1125.— Dworschak and Poore, 2018: 68.

Ctenochelidae .— Sakai, 2005b: 235.— Sakai, 2011: 485–486.— Dworschak et al., 2012: 189–190.— Poore and Dworschak, 2017: 122 (synonymy).

Pseudogourretiinae Sakai, 2005b: 230.

Dawsoniinae Sakai, 2006: 1276–1277.— Sakai, 2011: 507.— Sakai, 2017a: 1124.

Ctenocheloidae (pro Ctenocheloididae ) Sakai, 2011: 595–596.— Poore, 2015b: 142 syn. nov.

Pseudogourretiidae Sakai, 2011: 507–508 , 523.

Tosacallianassidae Sakai, 2016: 813 .

Diagnosis. Rostrum spike-like, longer than wide; median carina absent, or rarely on rostrum only; gastric carinae absent; cervical groove well defined; suture between ocular lobe and end of linea thalassinica horizontal or oblique in lateral view; anterior branchiostegal margin sinusoidal or semicircular, or with deep obtuse notch leading to oblique ridge; anterior branchiostegal lobe simple, scarcely calcified, merging smoothly with anterodorsal branchiostegal angle and anterolateral margin of carapace; posterior margin of carapace without lateral lobes. Pleomere 1 without anterolateral lobes, weakly chitinised. Eyestalks flattened, contiguous, with subdistal dorsal cornea. Antennal scaphocerite simple, triangular. Maxilla scaphognathite without long seta on posterior lobe extending into branchial chamber. Maxilliped 1 epipod with acute anterior lobe lying alongside exopod. Maxilliped 3 propodus longer than wide, not prominently lobed on lower margin; dactylus slender, digitiform, with setae irregularly spaced along all margins. Cheliped merus lower margin smooth or with prominent proximal tooth; major cheliped with cylindrical palm, fingers elongate and pectinate, or with distinctively flattened palm, sometimes with strong crest above and below. Pereopod 3 propodus rectangular or oval, up to twice as long as wide, with proximal lobe on lower margin, without distal spiniform setae on lateral face or lower margin. Pereopod 5 semichelate (fixed finger closing on proximal part of dactylus), dactylus a twisted plate longer than finger. Female pleopod 2 rami narrower and with more reduced setation than pleopods 3–5; endopod flattened and 2–3 times as long as wide. Pleopods 3–5 with oblique peduncles, endopods oval, exopods attached laterally, not proximally lobed, shorter than and barely overlapping endopods, or with oblique peduncles meeting mesially, endopods triangular, with straight mesial margin, exopods attached laterally, proximally lobed, longer than and enclosing endopods; appendices internae elongate, much longer than wide. Uropodal exopod without elevated dorsal plate, or with margin divided by notch.

Remarks. Robles et al. (in press) found Ctenochelidae to have strong molecular support and two morphological synapomorphies. The character states shared by members of this family are maxilliped 3 with a prominent toothed crista dentata, usually extending beyond the meral distal margin, and a semichelate pereopod 5, its dactylus a twisted plate longer than the finger. Two clades, ctenochelids s.s. and gourretiids, were supported by morphological characters but not by molecular relationships.

Manning and Felder (1991) treated Ctenochelidae as one of two “callianassid-like families”, distinguished from Callianassidae by the presence of an appendix masculina on the male pleopod 2, which was incorrect, as realised later by Felder and Manning (1994: 352), a longitudinally carinate uropodal exopod, lacking a dorsal plate and a carapace usually with a cardiac prominence. Their arrangement was followed by Poore (1994). The genera of Ctenochelidae known to these authors are treated in three families here. Sakai (1999c) included only Paracalliax beside the type genus and excluded Dawsonius and Gourretia in a new subfamily Gourretiinae . Sakai (2005b) elevated the taxon to family rank, retaining its single subfamily that he ignored in Sakai (2011), and confined Ctenochelidae to Ctenocheles .

As pointed out by Poore (2015b), Sakai’s (2011) diagnosis of his new family Ctenocheloididae (as Ctenocheloidae ) is virtually the same as Anker’s (2010) diagnosis of Ctenocheloides and was presented without a strong argument for why family status is to be preferred over genus status for its single species. We treat Ctenocheloididae as a junior synonym. Poore and Dworschak (2017) synonymised three taxa erected by Sakai and Türkay (2016), Tosacallianassidae with Ctenochelidae , Tosacallianassa with Ctenocheles , and T. hatasagaensis with Ctenocheles balssi .

Gourretiinae was established by Sakai (1999c) as a subfamily of Callianassidae for Gourretia de Saint Laurent, 1973 , and Dawsonius Manning and Felder, 1991 . Sakai (2004) elevated the taxon to family level and added Callianopsis de Saint Laurent, 1973 , and two new genera, Laurentgourretia and Paragourretia . Pseudogourretiinae was then added for another new genus, Pseudogourretia Sakai, 2005b . Sakai (2006) recognised Callianopsinae and Pseudogourretiinae as subfamilies of Gourretiidae and added Dawsoniinae for Dawsonius . All subfamilies were ignored in Sakai’s (2011) synthesis where four of the genera discussed earlier were included; Paracalliax was added although it had earlier been treated as member of its own family (see discussion under Paracalliacidae below), and Callianopsis was excluded (see Callianopsidae discussed above).

Sakai (2017b) radically dissected Gourretiidae , introducing five new genera. Paragourretia and Dawsonius were treated as synonyms of Gourretia , Paracalliax was retained and his earlier genus Pseudogourretia ignored. Justification of the new genera centred on differences between the male pleopods 1 and 2. He stressed the significance of these sexually differentiated structures, citing their importance in the taxonomy of other decapods and their greater significance than the few cheliped characters available to palaeontologists ( Hyžný and Klompmaker, 2015). However, he took no account of pleopodal developmental as individuals mature from juveniles to adults. All five of Sakai’s (2017b) new genera are herein synonymised with either Gourretia or Paragourretia .

On strictly cladistic criteria, Dawsonius is a senior synonym of Paragourretia on molecular evidence (Robles et al., in press). But the genus has unique apomorphies apparent in the morphological treatment, pleomere 6 with triangular lateral projections, maxilliped 3 exopod absent and pereopod 3 with a triangular propodus proximally produced on the lower margin. Otherwise the two genera have the same uropods, male pleopods and chelipeds.

Pseudogourretia , said by Sakai (2005b) to possess pleurobranchs, was found by Dworschak and Poore (2018) to not have pleurobranchs, as all callianassoids, and the genus was synonymised with Gourretia . The only character placing the sole species, P. portsudanensis in Gourretia rather than Paragourretia is the oval pereopod 3 propodus; chelipeds and uropods are missing from the only specimen. The family erected for it ( Sakai,2011) likewise is a junior synonym of Ctenochelidae .

Figures

Figure 16. Diagnostic characters for genera of Ctenochelidae. Pleon (suture between pleomeres 2 and 3 indicated): a, Ctenocheles; b, Ctenocheloides. Pleomere 6, telson, uropod: c, Dawsonius; d, Gourretia; e, Paragourretia; f, Laurentgourretia. Rostrum, eyestalks, antennules, antennae: g, h, Ctenocheles; i, Ctenocheloides; j, k, Laurentgourretia. Original illustrations: f, j, k, Laurentgourretia rhopalommata, MNHN-IU-2014-11417.

Figure 17. Diagnostic characters for genera of Ctenochelidae. Major cheliped: a, Ctenocheles; b, Ctenocheloides; c, Kiictenocheloides; d, Gourretia. Minor cheliped: e, Ctenocheloides; f, Kiictenocheloides; g, h, Paragourretia; i, Gourretia. Maxilliped 3: j, Gourretia. Male coxa 5: k, Laurentgourretia. Male pleopods 1, 2: l, m, Laurentgourretia. Original illustrations: k–m, Laurentgourretia rhopalommata, MNHN-IU-2014-11417.